KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 27. N:0 3. 121 



Var. horealis KCtz (1844). — L. 0,oi3 to 0,o25 mm. Striae 21 to 24 in 0,oi mm. — A. bo- 

 realis KCtz Bac. p. 108 PI. Ill f. 18. V. H. Syn. PI. I f. 20. A. salina /? minor V. H. Syn. p. 57. 



Fresh or brackish water: Helgoland (Klitz), Gulf of Bothnia! 



Var. fossilis Pant. (1889). — L. 0,032 mm. Striae 22,5 in 0,oi mm. —A. salina var. fossilis 

 Pant. II p. 39 PI. Ill f. 47. 



Brackish water: Hungary, fossil (Pant.). 



Var. angularis V. H. (1880). — Frustule in L. 0,o25 to 0,043; B. 0,oi to 0,oi5 mm. slightly 

 constricted in the middle. Striae 20 to 23 (18 according to Van Heurck) in 0,oi mm. Divisions 

 of the zone about 14 in 0,oi mm., distinctly striate, — A. angularis V. H. Syn. p. 57 PL If. 21. 

 A. angulosa var. lyrata V. H. Syn. f. 22. A. hyhrida Grun. V. H. Syn. p. 57 V. H. T. N:o 12. 

 A. bullosa var. lineolata H. L. Smith T. N:o 611. 



Marine: England! Belgium! 



Var. hungarica Cl. - V. in length 0,044; B. 0,oi. Ventral margin straight. Striae 20 in 

 0,01 mm. — A. acutiuscula var. fossilis Pant. II p. 35 PI. II f. 29. 



Brackish water: Hungary, fossil (Pant.). 



Var. protracta Pant. (1889). — L. of V. 0,08; B. 0,oo7 mm. Ventral margin convex. Ends 

 protracted, capitate. Striae distinctly punctate 17,5 to 19 in 0,oi mm. — A. protracta Pant. II 

 p. 39 PI. I f. 5. 



Brackish water: Hungary, fossil (Pant.). 



12. A. acutiuscula Kutz (1844). — Frustule eUiptic-lanceolate, with subrostrate and trun- 

 cate ends. L. 0,035 to 0,o7; B. 0,oi9 mm. Zone with numerous divisions, about 11 in 0,oi mm., 

 transversely striate; striae 18 to 20 in 0,oi mm. V. narrow, 10 to 12 times as long as broad, 

 with subcapitate ends and straight ventral margin. Median line close to the ventral margin. 

 Striae 13 to 18 in 0,oi mm. finely, but distinctly punctate. — Bac. p. 108 PI. V f. 32. V. H. 

 Syn. p. 57 PI. I f. 18. A. lineaia Greg. Diat. of Clyde p. 512 PI. Xn f. 70 (1857) A. S. Atl. 

 XXVI f. 59. A. eoffceiformis var. Salinarum Grun. Foss. D. Osterr. Ung. p. 148 (1882). A. striata 

 Pant. II p. 39 PL II f. 31 (1889)? A. striolata Pant. II p. 39 PL II f. 25 (1889)? A. juvenalis 

 Pant. IH PL XIII f. 199 (1893). 



Brackish and marine: Greenland! Spitsbergen! Finmark! Sea of Kara! Baltic! North Sea! 

 Morocco! Balearic Islands! Caspian Sea (Grun.), Hungary, fossil Czekehaza! Cape May! Samoa! 



Var.? subconstricta Grun. (1878). — Frustule slightly constricted in the middle. L. 0,035 

 to 0,04 5; B. 0,011 to 0,012 mm. Striae 15 to 17 in 0,oi mm., on the zone fine. — Casp. Sea Alg. 

 p. 8 PL III f. 5. 



Brackish water: Caspian Sea (Grun.), N. "Wales. 



Var.? eonstrida Grun. (1878). — Larger than the var. subconstricta. Striae 12 to 14 in 

 0,01 mm. — Casp. Sea Alg. p. 8. 



Marine: Tahiti, Tonga Islands, Samoa (Grun.), Seychelles (Van Heurck Coll.!) 



A. acutiuscula differs from A. eoffceiformis in its larger size, coarser striae, and distinctly 

 striate zone, but all these characteristics are variable, and in fact both species are connected by 

 intermediate forms, as is also the case with A. macilenta Greg. 



Pantocsek has described under the name A. Loczyi (II p. 37 PL V f. 93) a form that seems 

 to belong to A. acutiuscula, but. the description does not agree with the figure, as the striae are 

 according to the description 11 in 0,oi mm. and on the fig. 14 to 15 in 0,oi mm. The variety 

 subconstricta may be identical with A. angularis and the var. constricfa with A. hinodis. 



13. A. macilenta Greg. (1857). — Frustule in outline lanceolate, with truncate ends. 

 L. 0,03 7 to 0,12 mm. Zone with numerous divisions, 7 to 8 in 0,oi mm., transversely striate; 

 striae 11 to 15 in 0,oi mm. V. semilanceolate with rostrate-capitate ends. Median line close to 

 the ventral margin. Striae 9 to 12 in 0,oi mm., obscurely punctate. 



K. Sv. Vet. Akad. Handl. Baud 27. N:o 3. 16 



